A Pair of Industry Bigwigs Talks Technology at the Detroit Auto Show

The Steering Column

May 2007
By
CSABA CSERE

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One of the things that elevates important auto shows, such as Detroit's, is the presence of industry movers and shakers. At the Detroit show in January, I had a chance to chat with Carlos Ghosn, the boss of both Nissan and Renault, and also with Klaus Dräger, the newly appointed head of research, development, and, oddly enough, purchasing at BMW.

You never want to go one-on-one with Ghosn without having done your homework because the man is so direct and focused that he'll leave you slack-jawed if you try to wing it with your questions. With American carmakers having just come off a disastrous year, caused in part by fuel prices, I was curious about Nissan's plans for fuel-efficient cars.

"When people look at cars," Ghosn said, "they want attractiveness and competitiveness. Competitiveness is the rational part. Attractiveness is the emotional part. All carmakers struggle to balance these two factors, which are also present in fuel-efficient cars. Fuel efficiency is not only mpg but also environmental friendliness — feeling good about buying a car is a part of fuel efficiency. The second part is very rational — balancing improved mpg versus higher purchase cost. An overall green program includes hybrid powertrains, fuel cells, electric cars, recycling, and more. We think hybrid cars can be incorporated into existing models. But the consumer will decide if this is what he wants."

These statements are perfectly in line with Nissan's modest goal of selling only about 12,000 hybrid Altimas this year. For all the hype about hybrids, now that there are a few hundred thousand of them on the road — enough, in my view, to satisfy the needs of the hard-core environmentalists — future sales growth will likely come only as gas gets more expensive and hybrid technology gets cheaper. As this is written, with gas having been less than $2.50 per gallon for at least six months, demand for hybrids has run out of steam. In fact, most hybrids, including the Prius, now have some degree of sales incentive, justifying, it would seem, Ghosn's tempered enthusiasm for them.

Even so, Ghosn doesn't want to get caught out if gas prices spike. He sees a strong future for diesels in America. "Diesel makes more sense in bigger cars than in smaller ones," he said. "And diesel is easier to adapt to a wide variety of vehicles than hybrid is. We will start by transforming our existing European diesels for America within the next five years." Interestingly, he also sees a strong future for electric cars "if a cheaper battery is developed."

In a more conventional vein, Ghosn makes strong claims for the continuously variable transmission available in virtually every Nissan car. "CVTs are 10 percent more fuel efficient." This was contrary to what I had been seeing, so Ghosn offered up a pair of Nissan Versas, one with a CVT and the other with a conventional four-speed automatic for us to test.

The results are in the box on this page. Our tests reveal that the CVT extracts more performance from the 122-hp, 1.8-liter four-banger than does the automatic, which is hardly surprising. The CVT can keep the engine very near its 6000-rpm peak for all but the first few feet of the quarter-mile, whereas the automatic lets the engine get as much as 1500 rpm off the power peak after each shift. Those excursions from peak power cost time once the two cars are launched.

But regarding fuel economy, we'll have to disagree with Nissan's boss. We found the reverse situation on a 280-mile test loop with the two cars driven simultaneously. Even though one might expect that at any speed or load the CVT keeps the engine operating closer to its most efficient point than can the four-speed automatic, there's one offsetting factor. A CVT varies its ratios by changing the spacing of the sheaves in its two pulleys, which causes the drive belt to ride higher or lower in each pulley. It takes a huge amount of force to control this pulley spacing, and CVTs employ a powerful hydraulic pump to generate the necessary force.

The power to drive this pump apparently exceeds the hydraulic losses in an automatic transmission, particularly when the lockup clutch is engaged. This difference in power loss saps the fuel efficiency of the CVT. Perhaps Nissan will ultimately find a solution to this issue, but many automakers have experimented with CVTs and most have given up on the technology.

According to BMW's Dräger, his company's fuel-efficiency advances don't include CVTs. "We plan to do 50-state diesels by 2008." BMW is also looking at easy energy improvements, such as expanding the use of electric water pumps and engaging the alternator to charge the battery only when the car is coasting. "There's five-to-ten-percent efficiency available from such simple energy recoveries," said Dräger.

BMW is also focused on the difficult task of keeping vehicle weight under control. "Cars are growing in wheelbase and track," continued Dräger. "It makes it more difficult to achieve the rigidity needed for performance and safety. To combat this problem, we have doubled the use of high-strength steel. Now, more than 50 percent of the body in white [the basic structure without exterior panels] is made using high-strength steel."

When asked about the future of the little-liked sequential manual gearbox, Dräger admitted that BMW was developing a new twin-clutch transmission for future M3 and M5 models. No doubt BMW will give this gearbox a highly creative name that sounds nothing like VW/Audi's DSG. But BMW is wise to acknowledge that such dual-clutch transmissions are the future of automated manuals.

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